Electrostatics is concerned with the field and potential of stationary electrical charges and electric charge distributions. Problems are this type are almost exclusively concerned with mathematics of geometries using the inverse-square law.
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When I connect in series two floating capacitors, one charged and the other not charged, does current flow?
Suppose I energize one capacitor by connecting it across a battery, allowing it to achieve some potential difference V0 across its plates, then disconnect it and allow both of its leads to float in ...
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0answers
86 views
Calculating Electric potential [closed]
A charge Q is distributed over two concentric hollow spheres radii a and b (b>a) such that their source charge densities are equal. Find the potential at the their common center
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1answer
321 views
linear charge density, surface charge density and volume charge density
What is the difference among linear charge density, surface charge density and volume charge
density.
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3answers
3k views
How is calculated the potential between two capacitors in series?
Suppose to have two capacitors in series:
The voltage in the middle point will be:
$$
V_X = V_1 \frac{C_1}{C_1+C_2}
$$
How can this be explained? It's been asked in electronics, and explained in ...
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votes
2answers
518 views
Charge distribution on a plate of Capacitor with Dielectrics .
I had this Homework Problem with a capacitor (parallel plate) that has a group of 3 dielectrics between it like so :
Now We were asked to find the equivalent capacitance and the distance of ...
0
votes
1answer
86 views
Gaussian Unit of Charge and Force
I just read that in the Gaussian Units of charge The Final equation in Coulomb's law is as simple as $$\boldsymbol{F}=\frac{q_1q_2}{r^2}$$
No $\epsilon_0$ no $4\pi$ like you have in the $\mbox{SI}$ ...
3
votes
2answers
455 views
Electrostatic Pressure Concept
There was a Question bothering me.
I tried solving it But couldn't So I finally went up to my teacher asked him for help . He told me that there was a formula for Electrostatic pressure ...
0
votes
0answers
191 views
Electric field caused by a wire [closed]
I want to check that my solution to this exercise is correct:
If a wire of length $a$ is located on the positive axis $x$, I want to find the electric field at a point $(0, y)$. The wire has a ...
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1answer
140 views
Residual Resistivity in alloys and metals
Residual Resistivity
I saw that the graph of resistivity to temperature of alloys like nichrome is like so
Meaning that even at 0 K it has some resistivity just like copper :
I read some where ...
2
votes
2answers
239 views
A Question From Jackson Electrodynamics
I have a question regarding Jackson's Classical Electrodynamics. Consider the equation
$$\varphi \left ( x\right )=\tfrac{1}{4\pi\epsilon _{0}} \int_V \frac{\varrho ( x )}{R}d^{3}x+\tfrac{1}{4\pi} ...
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votes
2answers
338 views
Voltage and current of positive lightning
For a physics issues investigation I chose to investigate what effects lightning could have on an aeroplane while in flight if it was struck and then go on to discuss some possible implications of ...
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1answer
159 views
Is a uniformly charged conducting plate the same as a uniformly charged conducting sheet?
Is it correct that a uniformly charged conducting plate is made up of two charged conducting sheets, that is, a charged conducting plate consists of four surfaces?
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1answer
48 views
Why isn't the force modelled which confines excess charge to remain inside a conductor?
Excess charge placed on a conductor distributes itself on the surface of a conductor. But why isn't the force which confines the charge to remain there, modelled in some way?
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1answer
320 views
Trajectories using Polar Coordinates
Once I asked my teacher how to find the trajectory of any particle that is acted upon any force.(Generally)
He Told me that I couldn't do it as I did not know polar coordinate geometry as of then but ...
1
vote
1answer
259 views
Dielectric in a parallel plate capacitor
Uniform charge: each atom has charge $q$.
Magnitude of dipole moment is $q s$, where $s$ is the distance the nucleus is shifted.
According to my notes, the charge on the surface of a dielectric in ...
2
votes
1answer
194 views
Existence Of Electric Field Lines
Can an Electric Field with field lines Like So Exist:
One Of my friends said it couldn't as the field lines here are not conservative ; so it cannot exist ; Is he right?
Or can it be made to ...
4
votes
2answers
328 views
Meaning of the phrase “dipole moment of the combination”
Here is a question I came across in a book:
Three point charges $-q$,$-q$ and $2q$ are placed on the vertices of an equilateral triangle of side length $d$ units.What is the dipole moment of the ...
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0answers
85 views
Two protons are separated by a ceratin distance. What should be the distance so as to balance their weight? [closed]
I never got the concept of 'balancing the weight'. This question is from electrostatics, and it's come for a proton and electron too. I would just like to get the concept cleared, because I have the ...
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1answer
194 views
Equipotential Contour mapping and making it 3D [closed]
I have seen Contour diagrams for Equipotentials . That are drawn like so:
I also saw One image for these contours that was in 3D (Negative Point Charge) :
I was Wondering If there's any ...
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2answers
394 views
Electricity & Magnetism - Is an electric field infinite?
The inverse square law for an electric field is:
$$
E = \frac{Q}{4\pi\varepsilon_{0}r^2}
$$
Here: $$\frac{Q}{\varepsilon_{0}}$$
is the source strength of the charge. It is the point charge divided ...
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votes
3answers
204 views
What's the right way to calculate charge on a capacitor?
How much charge is on each plate of a 4.00-F capacitor
when it is connected to a 12.0-V battery?
I said 2.4 x 10^-5 C because there are two plates of a parallel plate capacitor. But the key said only ...
0
votes
2answers
327 views
Capacitors in series
I need some explanations on the green underlined sentences.
1) "Must continue to have zero net charge..." What if the $\ C_2$ had +2Q on the left plate and -Q its right plate? The net charge ...
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vote
3answers
330 views
Is this really how a capacitor works? Why doesn't it behave like a resistor?
My book says a capacitor is two conducts being connected by an insulator. Now let's take a parallel plate capacitor to simplify the problem I have.
Suppose I got two parallel plate capacitor in ...
1
vote
3answers
399 views
Electrostatic Potential Energy
I have read many books on Mechanics and Electrodynamics and the one thing that has confused me about electrostatic potential energy is its derivation .One of the classical derivations is :
...
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1answer
472 views
Solving Poisson-Boltzmann equation for flat surface without excess salt
I'm trying to understand the solution of Poisson-Boltzmann (PB) equation as I read it in a review. The surface is uniformly charged and flat. I am only considering the $x$ direction.
The PB equation ...
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0answers
197 views
Potential of two concentric spheres not charged [closed]
In the problem we got two concentric spheres with radius $a$ and $b$ respectively. the spheres are connected by thin wire and both spheres are thin. at distance $R$ from the center they put a charge ...
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votes
1answer
72 views
Flux if there were only one type of charge in the universe
There was this question that i saw in a book and it also had an answer given.
The Question was:
If there were only one type of charge in the universe, then:
$\phi = \oint ...
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1answer
103 views
Why is the flux 0? I don't understand this concept
!
Why does it say that the flux due to q_2 and q_3 through S is 0? Doesn't it contain a nonzero charge q_1?
Does anyone also know the difference between "no charge" vs "net charge is 0"? My book ...
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votes
2answers
707 views
Electric potential due to a point charge in Gaussian/CGS units
I learned electrostatics in SI units. In SI, the electrostatic potential due to a point charge $q$ located at $\textbf{r}$ is given by
$\Phi(\textbf{r}) = \frac{q}{4 \pi \epsilon_0 |\textbf{r}|}$.
...
3
votes
1answer
2k views
Why we cannot use Gauss's Law to find the Electric Field of a finite-length charged wire?
One of my physics books has a nice example on how to use Gauss's Law to find the electric field of a long (infinite) charged wire. However, at the very end of the example, the author ends by saying ...
4
votes
4answers
2k views
Infinitely charged wire and Differential form of Gauss' Law
I have tried calculating the potential of a charged wire the direct way. If lambda is the charge density of the wire, then I get
$$\phi(r) = \frac{\lambda}{4 \pi \epsilon_0 r} \int_{-\infty}^\infty ...
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2answers
294 views
Electric fields in/around conductors
So according to my notes, the field inside a conductor is zero. But what, exactly, is meant by inside?
I think we are in electrostatics for the purpose of this question.
The reason it is zero is ...
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2answers
895 views
Derivation of Electric Force between Parallel Plates
So the electric field between two parallel plates is given by $E = V/d.$ How do you derive this?
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1answer
50 views
charge moves if you scuff the rag with your shoes
Why is that when you scuff with your shoes on, charges move (since electrometer moves back and forth), but if you don't have your shoes on, the electrometer doesn't move.
Here's the corresponding ...
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2answers
50 views
How does an object regains its neutrallity after being charged by rubbing?
Objects (like comb)can be charged by rubbing as charged particles, particularly, electron are transferred from one object to other. This can be seen as object (comb) attracts small bits of paper. ...
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votes
3answers
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Why a glass rod when rubbed with silk cloth aquire positive charge and not negative charge?
I have read many times in the topic of induction that a glass rod when rubbed against a silk cloth acquires a positive charge. Why does it acquire positive charge only, why not negative charge?
It ...
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vote
1answer
128 views
Where is the flaw in deriving Gauss's law in its differential form?
From the divergence theorem for any vector field E,
$\displaystyle\oint E\cdot da=\int (\nabla\cdot E) ~d\tau$
and from Gauss's law
$\displaystyle\oint E\cdot ...
2
votes
2answers
211 views
Why does the induced charge have to have the same magnitude as the inducing charge?
Why is it that the total induced charge on a conducting, grounde,d infinite plane must be of the same magnitude as the inducing charge?
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votes
3answers
956 views
“Find the net force the southern hemisphere of a uniformly charged sphere exerts on the northern hemisphere”
This is Griffiths, Introduction to Electrodynamics, 2.43, if you have the book.
The problem states Find the net force that the southern hemisphere of a uniformly charged sphere exerts on the ...
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votes
3answers
806 views
Charge Distribution on a Parallel Plate Capacitor
If a parallel plate capacitor is formed by placing two infinite grounded conducting sheets, one at potential $V_1$ and another at $V_2$, a distance $d$ away from each other, then the charge on either ...
3
votes
4answers
2k views
In electrostatics, why the conductor is an equipotential surface?
Since the electric field inside a conductor is zero that means the potential is constant inside a conductor, which means the "inside" of a conductor is an equipotential region.
Why books conclude ...
2
votes
3answers
4k views
In electrostatics, why the electric field inside a conductor is zero?
In electromagnetism books, such as Griffiths or the like, when they talk about the properties of conductors in case of electrostatics they say that the electric field inside a conductor is zero.
I ...
1
vote
2answers
1k views
Is a charged particle at rest affected by magnetic field?
It is known that particles such as electrons and protons bear electric charge, but not a magnetic charge. When these particles are at rest, are they somehow affected by magnetic field?
The similar ...
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votes
2answers
455 views
Boundary conditions for static electric field
Consider a surface that carries surface charge density. In electrostatics, boundary conditions are studied by showing that there is a discontinuity in the normal component of the electric field across ...
3
votes
1answer
95 views
Scaling of Static Electric Field
The electric field of a point charge goes like $\displaystyle\frac{1}{r^2}$
The electric field of an infinite line goes like $\displaystyle\frac{1}{s}$
The electric field of an infinite plane is ...
5
votes
1answer
166 views
What equation describes the electrostatic potential in these circumstances?
I have a solver for Poisson's equation and it works nicely. It uses finite differences. It works in the presence of multiple dielectrics.
It also solves the Poisson Boltzmann equation. That is, fixed ...
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votes
2answers
93 views
static shock=thermocouple?
I used to live in Boston. Near my complex, there was an apartment complex with lots of our friends. Anyways, that place had faulty heating most of the time; mainly in the corridors. They were pretty ...
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0answers
72 views
Is putting a charged balloon up to a neutral wall polarization AND temporary induction, or just polarization?
Is putting a balloon that is charged up against a wall and having it stick polarization AND charging by temporary induction, or just polarization?
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0answers
220 views
Dielectric in Parallel Plate Capacitor
Given a parallel plate capacitor of width $w$, length $l$, with a dielectric moving along the length $l$. Let the dielectric be from $x$ onwards.
The capacitance will be $\frac{w \epsilon_0}{d} ...
3
votes
1answer
407 views
Trying to understand Laplace's equation
I'm struggling here so please excuse if I'm writing nonsense.
I understand that the gravitational potential field, a scalar field, is given by $$\phi=\frac{-Gm}{r}$$
where $\phi$
is the ...
